A person who believes he has talents, skills and/or intelligence he simply doesn't possess. Delusioniods frequently are immensely unskilled and often tragically bad at the pursuit they claim to master. A delusioniod will not accept criticism or reality. A delusioniod will spend more time berating and bullying his detractors than he will honing his craft. The largest concentration of delusioniods aspire to be singers and actors. There are no successful or famous delusioniods.

Ishtar is the best, worst movie ever made about delusioniods.
If Great Aunt Madeline really thinks anyone will pay her to strip, she is a total delusioniod.